The recent introduction of multi-slice (especially 4-slice) CT scanner opens up new frontier for technology and clinical application developments in this field. This research is to develop new optimized imaging techniques that, supplementary to the current multi-slice CT gold- standard scan mode, will improve thin-slice imaging capability at only slightly reduced volume coverage speed, for challenging applications such as temporal bone imaging. In phase I, guided by a new z-sampling analysis method developed by the Principal Investigator, the z-sampling efficiency of multi-slice CT will be studied as a function of the helical pitch. Optimal helical pitches will be identified, resulting in a finer z-sampling spacing of 1/3 or 1/4 (vs. the current +) of the detector row aperture. The corresponding reconstruction algorithms, including both helical interpolation (in Phase I) and z sharpening filter or image deblurring (in Phase II), will be developed to optimize the thin-slice imaging performance. The performance tradeoffs of these new imaging techniques will be characterized with the gold-standard scan mode on current multi- slice CT (in Phase I) and other scan modes proposed (in Phase II). The clinical benefits of these new imaging techniques will be identified in Phase II. PROPOSED COMMERCIAL APPLICATIONS: Thin-slice imaging capability is an important differentiating factor and a key selection criterion for multi-slice CT scanners. This research will develop an optimized imaging (scan and reconstruction) technique to maximize the performance of high priced ( million-dollar) multi-slice CT scanners. Thus, the proposed research will generate great clinical benefits for CT users and substantial commercial benefits for CT manufacturers.